URBAN TACTICS

URBAN TACTICS; I'll Take Mannahatta

By MARGUERITE HOLLOWAY

Published: May 16, 2004

IN 1808, a young man began hiking the forests and fens, streams and ravines, marshes and meadows of Manhattan, lugging chains and surveying equipment and possessed of such determination that he endured assaults by dogs and, legend holds, lobbed vegetables and numerous arrests for trespassing.

For 13 years, John Randel Jr. wrestled the wildness of the island as he imposed his vision upon it: gone, in his mind's eye, were the hills and ponds, the towering chestnut trees, the unruly outcroppings. Randel was mesmerized by the image of a magnificent, neatly ordered metropolis. Faithful to this view and to the government officials who wanted a plan for the rapidly growing New York, Randel lay down the great gray grid, eliminating hills, easing the eccentricities of the untamed landscape. The Randel Survey, or Commissioners' Plan, as the result is called, decided Manhattan's future.

Sometimes, as Eric W. Sanderson strolls over the flat terrain of a decapitated hill or a salt marsh suffocated by landfill, he thinks of Randel. Mr. Sanderson, too, walks the island armed with surveying equipment; he, too, possesses determination, fear of attracting police attention and a vision at odds with his surroundings. Mr. Sanderson might need 13 years as well. But however long it takes, he intends to remove Randel's grid.

Removing, or at least tempering, the hand of man is what Mr. Sanderson most likes to do. A landscape ecologist for the Wildlife Conservation Society, based at the Bronx Zoo, he works with other scientists to save the world's wild places and creatures. He helps protect jaguars in Central America, primates in Congo and hundreds of acres of new parkland in Gabon.

One afternoon in 1999, a year after moving to New York from California, he wandered into the Strand and bought a book that changed his life. The book was called ''Manhattan in Maps: 1527-1995,'' and thumbing through it, he caught sight of a beautiful British Headquarters map, circa 1782. ''It was the first time a full color version had been reproduced,'' he recalled. ''It was virtuoso cartography.''

The map was indeed remarkable. The military surveyors and mapmakers stationed in Manhattan between 1776 and 1783 were among the world's best, and their anxiety about George Washington and his Continental Army prompted them to measure and draw every feature of the landscape that might be important in waging or responding to an attack. Except for a few clusters of settlement and a network of roads, the island looked much as it had before Europeans settled.

To Mr. Sanderson, the meticulous portrayal of the island's original topography evoked Manhattan primeval. He began to imagine the trees that thrived on north-facing slopes; he could see where black bear lumbered and wolves hunted elk, where fish spawned. He could envision what Henry Hudson saw in 1609 as he sailed along Mannahatta, which in the Lenape dialect most likely meant ''island of many hills.''

That evening, Mr. Sanderson embarked on his own voyage of discovery. He decided to create a computer model and guidebook that would restore Mannahatta to modern New Yorkers. If he could use his computer to accurately lay the old map on top of the modern grid, he figured, he could come up with a block-by-block description of the original topography. If he threw in climate information for the 17th century (which he didn't have) and information about soil types and Lenape land use (ditto), he could determine which plants lived where (once he got his hands on a list of species native to the island). If the plants were in place, he could add the associated birds and animals, along with lichens, mosses and fungi.

If he succeeded with what he came to call the Mannahatta Project, New Yorkers and tourists could stand at any street corner, and conjure the birds and the beasts, the woods and wetlands of 1609 -- ''as pleasant with Grasse and Flowers and goodly Trees, as ever they had seene, and very sweet smells came from them,'' as Hudson's first mate, Robert Juet, wrote.

MR. SANDERSON began by identifying about 50 landmarks on the map that he knew still existed, like the steps of Trinity Church, the site of Fort Tryon and the Great Hill in Central Park. Starting in early 2001 with his wife, Han-Yu Hung, and his infant son, he set out to obtain Global Positioning System coordinates for those sites. Over several months, Mr. Sanderson visited those sites, and found about 25 he could successfully use to align the British map with one from today.

Through his own research and budding collaborations with many New York scientists, Mr. Sanderson discovered some interesting facts. Mannahatta had 21 lakes or ponds, 62 miles of streams, at least 10,000 species (including invertebrates, like insects) and some 45 different ecosystems, from pine barrens to offshore eelgrass beds. Although cultivated and seasonally burned in places by the Lenape, Mannahatta was a gorgeous place before the ecosystem was transformed by pigs, cattle, newly introduced plants and pests, and Dutch farmers.